Back flushing is performed by feeding water into the outlet port of the system. Allow water to flow out of the inlet connection at a rate of one gallon per minute. This reverse flow process mechanically cleans the resin bed. If back flushing is being done along with a regeneration process the back flush should be done first. Back flush for 20-30 seconds and you will use the restricted side of the y-valve which has a pinhole plug in it for 1 GPM.